In cats, black fur color is caused by an X-linked allele; the other allele at this locus causesorange color. The heterozygote is tortoiseshell. What kinds of offspring would you expect fromthe cross of a black female and an orange male?

In birds, sex is determined by a ZW chromosome scheme. Males are ZZ and females areZW. A recessive lethal allele that causes death of the embryo is sometimes present on the Zchromosome in pigeons. What would be the sex ratio in the offspringof a cross between a malethat is heterozygous for the lethal allele and a normal female?

A) 2:1 male to female

B) 1:2 male to female

C) 1:1 male to female

D) 4:3 male to female

E) 3:1 male to female

C) 1:1 male to female

I believe the answer to this is A) 2:1 male to femaleYes, it is A.Explanation: There is a 50% chance that a bird that was going to born female(of which there is a 50% of) will get the lethal recessive allele. All the males will not be affected by the allele(though 50% of the males will be carriers). So, using a punnett square, it can be seen that for every four possible offspring, one female will never be born for she received the lethal allele(this bird not can be included in the ratio), one female will be born because she did not get the allele, one male will be born a carrier, and one male will be born without the allele. 2 Males born : 1 female born.

A man who is an achondroplastic dwarf with normal vision marries a color-blind woman ofnormal height. The man's father was six feet tall, and both the woman's parents wereof averageheight. Achondroplastic dwarfism is autosomal dominant, and red-green color blindness is X-linked recessive.

How many of their daughters might be expected to be color-blind dwarfs?